5.f. doesn't identify the target time for C only. It only mentions that the target length will be announced for Div. C only (since Div. B already knows the target length). The target time concept applies to both B and C. The reference to Div C is for the variable length that must be announced.

No. A breadboard with discrete resistors and/or basic transformers is not an integrated circuit. Note though that some types of resistors and transformers ARE integrated circuits and hence are not allowed.

An integrated circuit is a circuit in which all or some of the circuit elements are inseparably associated and electrically interconnected so that it is considered to be indivisible for the purposes of construction and commerce. Most resistors and capacitors are not integrated circuits. Nearly all transistors and op-amps are integrated circuits.

Yes because it is not hovering unless air is coming out. The air must have some way of escaping (i.e. it should need to be actively replenished for the device to work, not just be a sealed inflatable chamber).

There is no set distance it must hover. If an event supervisor, from a normal observation point without having to get up and close to the hovercraft, can visually see it move down when pushed, then yes it levitates.

Note there is an official rules clarification related to this, available at: https://www.soinc.org/official_rules_clarif The integrated circuit prohibition refers to all components (including voltage regulators / arduinos) other than those specified in the rules clarification.